JP2023516720A - Overvoltage characteristic evaluation device and overvoltage characteristic evaluation method for battery - Google Patents

Abstract

An overvoltage characterization device for a battery according to the present invention comprises a sensing unit configured to measure the current and voltage of the battery, and a measuring capacity during a discharge event following a polarization-induced pretreatment for the battery. a controller configured to determine the history and the measured voltage history. The control section determines a first measured voltage curve indicating a correspondence relationship between the measured capacity history and the measured voltage history. The control unit determines a second measured voltage curve indicating a correspondence relationship between the depth-of-discharge history obtained by normalizing the measured capacity history to the total discharge capacity of the measured capacity history and the measured voltage history. Further, the control unit differentiates the measured voltage history with respect to the discharge depth history to determine a differentiated voltage curve. The control unit compares the differential voltage curve with a reference differential voltage curve to determine overvoltage characteristic information related to the polarization induction pretreatment.

Description

The present invention relates to technology for evaluating overvoltage characteristics due to battery polarization.

This application claims priority based on Korean Patent Application No. 10-2020-0096200 filed on July 31, 2020, and all contents disclosed in the specification and drawings of that application are incorporated into this application. .

Recently, the demand for portable electronic products such as notebook PCs, video cameras, mobile phones, etc. is increasing rapidly, and the development of electric vehicles, energy storage batteries, robots, satellites, etc. is in full swing. Research on possible high performance batteries is actively underway.

Currently commercialized batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries have almost no memory effect compared to nickel-based batteries, and are easy to charge and discharge. It is in the limelight due to its advantages of being free, having a very low self-discharge rate and having a high energy density.

Voltage and current are fundamentally required battery parameters in estimating battery performance, such as state of health (SOH) and state of charge (SOC). The capacity (or change thereof) of the battery can be determined based on current measurements, such as using coulomb counting.

Differential Voltage Analysis (DVA) determines the differential voltage curve by differentiating the measured voltage curve that shows the correspondence between the capacity and voltage of the battery, and then measures the size of the characteristic portion shown in the differential voltage curve. A degradation parameter of the battery is determined based on the change in height and/or the change in position. Degradation parameters include, for example, positive or negative electrode capacity loss, lithium deposition, and the like.

Conventionally, when determining the degradation parameter using DVA, the overvoltage reflected in the measured voltage curve due to polarization (e.g., the concentration gradient on the surface of the active material) acts as a kind of noise on the differential voltage curve. . Therefore, the process of obtaining the measured voltage curve should be performed while intermittently discharging or charging the battery at a low current (e.g., less than 0.5 C-rate) in order to maximize the suppression of the polarization that induces overvoltage. is normal. As a result, although overvoltage due to polarization is an important parameter affecting battery degradation, it is difficult to obtain battery overvoltage characteristics in conventional DVAs.

In addition, in order to develop a battery with excellent safety and performance, it is important to understand the relationship between the polarization depending on the usage conditions of the battery and the resulting overvoltage characteristics.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for evaluating the overvoltage characteristics of a battery using a DVA.

Other objects and advantages of the present invention can be understood from the following description and will be more clearly understood from the examples of the present invention. Also, the objects and advantages of the present invention can be achieved by means and combinations thereof shown in the claims.

According to one aspect of the present invention, an overvoltage characterization apparatus for a battery includes a sensing unit configured to measure current and voltage of the battery, and and a control unit configured to use the sensing information acquired from the sensing unit to determine a measured capacity history and a measured voltage history that indicate time-series changes in capacity and voltage of the battery. The controller is configured to determine a first measured voltage curve indicating a correspondence relationship between the measured capacity history and the measured voltage history. The control unit is configured to determine a second measured voltage curve indicating a correspondence relationship between the depth of discharge history obtained by normalizing the measured capacity history to the total discharge capacity of the measured capacity history and the measured voltage history. be done. The controller is configured to differentiate the measured voltage history with respect to the depth of discharge history to determine a differentiated voltage curve from the second measured voltage curve. The controller is configured to compare the differential voltage curve with a reference differential voltage curve to determine overvoltage characteristic information related to the polarization induction pretreatment.

The discharge event may include a constant current discharge from a first point in time to a second point in time. The first point in time is a point in time when the voltage of the battery is equal to a first critical voltage. The second time point is the same time point as the second critical voltage when the voltage of the battery is lower than the first critical voltage.

The control unit may be configured to determine an overvoltage concentration section, which is a range in which a differential voltage difference between the differential voltage curve and the reference differential voltage curve is equal to or greater than a critical difference in the entire range of the depth of discharge history. The overvoltage characteristic information includes the overvoltage concentration section.

The control unit may be configured to determine an area of an overvoltage concentration region defined by the overvoltage concentration section, the differential voltage curve, and the reference differential voltage curve. The overvoltage characteristic information further includes the area of the overvoltage concentration region.

The area indicates the amount of overvoltage accumulated in the battery over the overvoltage concentration interval.

The control unit divides the integrated value of the differential voltage difference over a reference range from a predetermined first depth of discharge to a predetermined second depth of discharge within the entire range of the depth of discharge history by the size of the reference range. to determine the critical difference.

The controller may be configured to determine the overvoltage concentration interval within the reference range.

According to another aspect of the present invention, a method for overvoltage characterization for a battery includes: using current and voltage sensing information of the battery obtained during a discharge event subsequent to polarization-induced pretreatment for the battery, Determining a measured capacity history and a measured voltage history indicating time-series changes in capacity and voltage of the battery; and determining a first measured voltage curve indicating a correspondence relationship between the measured capacity history and the measured voltage history. determining a second measured voltage curve indicating a correspondence relationship between the depth of discharge history obtained by normalizing the measured capacity history to the total discharge capacity of the measured capacity history and the measured voltage history; and differentiating the history with respect to the depth-of-discharge history and determining a differential voltage curve from the second measured voltage curve; and determining.

The step of determining the overvoltage characteristic information related to the polarization induction pretreatment includes overvoltage concentration in a range in which a differential voltage difference between the differential voltage curve and the reference differential voltage curve is equal to or greater than a critical difference in the entire range of the depth-of-discharge history. Determining the interval may be included.

Determining overvoltage characteristic information related to the polarization induction pretreatment may further include determining an area of an overvoltage concentration region defined by the overvoltage concentration section, the differential voltage curve, and the reference differential voltage curve.

According to at least one embodiment of the present invention, a DVA can be used to evaluate the overvoltage characteristics of a battery. In particular, the measured capacity history of the measured voltage curve obtained during the discharge event that follows the polarization-induced pretreatment for the battery is normalized to the depth of discharge history (0-100% range), and the measured voltage history and the measured capacity The correspondence relationship with the history can be converted into the correspondence relationship between the measured voltage history and the discharge depth history. Accordingly, as an evaluation result, it is possible to acquire an overvoltage concentrated section in which the overvoltage characteristics of the battery subjected to the polarization induction pretreatment appear intensively.

Also, according to at least one embodiment of the present invention, as a result of the evaluation, it is possible to additionally obtain the magnitude of the overvoltage accumulated over the overvoltage concentration interval.

The effects of the present invention are not limited to the effects described above, and other effects of the present invention not mentioned will be clearly understood by those skilled in the art from the description of the claims.

The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the detailed description of the invention. It should not be construed as being limited only to the matters described in the drawings.

1 is a diagram illustrating the configuration of a battery evaluation system according to the present invention; FIG. FIG. 5 is a diagram for explaining the relationship between the magnitude of overvoltage and the measured voltage curve; FIG. 5 is a diagram for explaining the result of normalization of the measured voltage curve; It is a figure for demonstrating the differential voltage curve corresponding to a measured voltage curve. FIG. 4 is a diagram for explaining an operation of determining overvoltage characteristics from a differential voltage curve; 4 is a flow chart illustrating a method for evaluating overvoltage characteristics of a battery according to a first embodiment of the present invention; FIG. 5 is a flow chart illustrating a method for evaluating overvoltage characteristics of a battery according to a second embodiment of the present invention; FIG.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be construed as being limited to their ordinary or dictionary meaning, and the inventors themselves should explain their invention in the best possible way. Therefore, it should be interpreted with the meaning and concept according to the technical idea of the present invention according to the principle that the concept of the term can be properly defined.

Therefore, the embodiments described in this specification and the configuration shown in the drawings are merely the most desirable embodiments of the present invention, and do not represent all the technical ideas of the present invention. It should be understood that there may be various equivalents and modifications that could be substituted for them at the time of filing.

Terms including ordinal numbers such as first, second, etc. are used to distinguish any one of various components from the rest, and the components are not limited by such terms.

It should be noted that throughout the specification, when a certain part "includes" a certain component, this does not exclude other components unless otherwise stated, and may further include other components. means that In addition, a term such as "controller" described in the specification indicates a unit that processes at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software. .

Furthermore, throughout the specification, when a part is "connected (connected)" to another part, this means not only "directly connected (connected)", It also includes the case where it is "indirectly connected (connected)" via another element in the middle.

FIG. 1 is a diagram illustrating the configuration of the battery evaluation system according to the present invention, FIG. 2 is a diagram for explaining the relationship between the magnitude of the overvoltage and the measured voltage curve, and FIG. FIG. 4 is a diagram for explaining the result of normalization, FIG. 4 is a diagram for explaining a differential voltage curve corresponding to the measured voltage curve, and FIG. 5 is a diagram for determining the overvoltage characteristic from the differential voltage curve. It is a figure for explaining.

Referring to FIG. 1, a battery evaluation system 1 is provided to evaluate battery B overvoltage characteristics. Battery B may be a lithium ion battery. Of course, the type of battery B is not particularly limited as long as it can be repeatedly charged and discharged.

The battery evaluation system 1 includes an overvoltage characteristic evaluation device 10 (hereinafter referred to as “evaluation device”) and a charge/discharge device 20 .

Charging/discharging device 20 is electrically connected to a current path for charging/discharging battery B. FIG. That is, the charging/discharging device 20 is provided to be electrically connectable in parallel to the battery B through a pair of terminals. Charging/discharging device 20 may include a constant current circuit that regulates the current rate (sometimes referred to as “C-rate”) of the current flowing through battery B. The charging/discharging device 20 is configured to adjust the current rate (sometimes referred to as “C-rate”) of the current for charging or discharging the battery B in response to an instruction from the evaluation device 10. . Of course, the charging/discharging device 20 can provide only one of constant current discharging function and constant current charging function.

The evaluation device 10 includes a sensing section 110 and a control section 120 . Evaluation device 10 may further include at least one of interface section 130 and temperature chamber 140 . Hereinafter, it is assumed that the evaluation device 10 includes the sensing unit 110, the control unit 120, the interface unit 130, and the temperature chamber 140. FIG.

Sensing unit 110 includes voltage sensor 111 and current sensor 112 . A voltage sensor 111 is provided to be electrically connected to the battery B in parallel. Voltage sensor 111 is configured to measure the voltage across battery B and generate a voltage signal indicative of the measured voltage.

A current sensor 112 is provided electrically connectable in series with the battery B through a current path connecting the battery B and the charging/discharging device 20 . Current sensor 112 is configured to measure the current flowing through battery B and generate a current signal indicative of the measured current.

The controller 120 may collect sensing information including synchronously acquired voltage signals and current signals from the sensing unit 110 .

The control unit 120 includes an ASIC (application specific integrated circuit), a DSP (digital signal processor), a DSPD (digital signal processing device), a PLD ( It can be implemented using at least one of a programmable logic device, a field programmable gate array (FPGA), a microprocessor, and other electrical units for performing functions. The controller 120 may have a built-in memory. Memory includes, for example, flash memory (registered trademark) type, hard disk type, SSD type (Solid State Disk type), SDD type (Silicon Disk Drive type, silicon disk drive type), multimedia card micro type, RAM (random access memory), SRAM (static random access memory), ROM (read-only memory) memory), electrically erasable programmable read-only memory (EEPROM), and programmable read-only memory (PROM). The memory may store data and programs necessary for arithmetic operations (a method to be described later) by the controller 120 . The control unit 120 can record data indicating the result of the arithmetic operation in the memory.

The controller 120 is operably coupled to the charge/discharge device 20 , the sensing unit 110 , the interface unit 130 and the temperature chamber 140 . Two structures are operatively coupled means that the two structures are directly or indirectly connected such that signals can be sent and received uni-directionally or bi-directionally.

The interface unit 130 is configured to support wired or wireless communication between the control unit 120 and the user's terminal 2 (eg, personal computer). Wired communication may be, for example, CAN (controller area network) communication, and wireless communication may be, for example, ZigBee (registered trademark) or Bluetooth (registered trademark) communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired/wireless communication between the control unit 120 and the terminal 2 of the user. The interface unit 130 may include an output device (eg, a display, a speaker) that provides information received from the control unit 120 and/or the user's terminal 2 in a form recognizable by the user.

During the discharge event of battery B, the control unit 120 determines the measured capacity based on the sensing information (i.e., the time series of current measurements and the time series of voltage measurements) collected from the sensing unit 110 at set intervals. History and measured voltage history may be determined. The measured capacity history indicates the chronological change in the discharge capacity of battery B from the start point to the end point of the discharge event. The measured voltage history shows the change in battery B voltage over time from the beginning to the end of the discharge event. In a discharge event, a relatively high discharge capacity in the measured capacity history corresponds to a relatively low voltage in the measured voltage history.

The controller 120 can record the measured capacity history and the measured voltage history in memory. A discharge event may include a constant current discharge. The discharge event may occur while temperature chamber 140 maintains the ambient temperature of battery B at a predetermined constant temperature.

The constant current discharge is performed from a first point in time when the voltage of the battery B is equal to the first critical voltage _VTH1 to a second point in time when the voltage of the battery B is equal to the second critical voltage _VTH2 which is lower than the first critical voltage _VTH1 . For example, the first threshold voltage _VTH1 may be the same as the end-of-charge voltage, which is a predetermined open circuit voltage (OCV) when the battery B is fully charged. The second critical voltage _VTH2 may be the same as the predetermined value of the open circuit voltage when the battery B is completely discharged, ie, the end-of-discharge voltage. The current rate of constant current discharge can be a high current of 6.5 C-rate, for example.

In FIG. 2, the X-axis (vertical axis) represents voltage, and the Y-axis (horizontal axis) represents discharge capacity. A first reference voltage curve 210 is obtained in advance through a discharge event for a reference battery (not shown) that has undergone a reference pretreatment, and a first measured voltage curve 220 has undergone a polarization induction pretreatment. It is obtained through a discharge event for battery B that is separated. A first reference voltage curve 210 indicates the correspondence relationship between the reference capacity history and the reference voltage history. The reference capacity history indicates the chronological change in the discharge capacity of the reference battery from the start point to the end point of the discharge event. The reference voltage history indicates the change in voltage of the reference battery over time from the beginning to the end of the discharge event. Battery B and the reference battery were manufactured to have the same electrochemical properties as each other.

Below are examples of each of the reference pretreatment and the polarization-induced pretreatment.

<Reference pretreatment>
Reference preprocessing may include the following series of steps.
1) Full discharge from a predetermined SOC (eg, 30%) using a predetermined first current profile 2) Left at a predetermined first temperature (eg, 80° C.) for a predetermined first time (eg, 6 hours) 3 ) full charge using a predetermined second current profile

<Polarization induction pretreatment>
Polarization-induced pretreatment can include the following series of steps.
1) From a given SOC (eg 30%) to full discharge using a given first current profile 2) Left at a given second temperature (eg 25°C) for a given second time (eg 3 hours)3 ) full charge using a predetermined second current profile

Comparing the reference pretreatment and the polarization-inducing pretreatment in the above example, the polarization-inducing pretreatment differs from the reference pretreatment in that the battery B is left at the second temperature (normal temperature) instead of the first temperature (high temperature). differ. Due to this difference, the discharge event is performed with the reference battery completely depolarized, while the battery B is subjected to the discharge event with the remaining polarization. Of course, the reference pretreatment is not limited to the above example, as long as it is performed to reduce the polarization of battery B below a certain level at the start of the discharge event. Similarly, the polarization-inducing pretreatment is not limited to the above example as long as it is performed to form a larger polarization in the battery B than the reference pretreatment.

After positioning battery B inside temperature chamber 140, the user may request evaluation device 10 to perform a polarization-induced pretreatment. The control unit 120 may control the charging/discharging device 20 and the temperature chamber 140 to sequentially perform the polarization induction pretreatment process according to a request received from the user's terminal 2 through the interface unit 130 . The temperature chamber 140 is provided with an internal space that can accommodate the battery B, and is a device capable of detecting and adjusting the temperature of the internal space (that is, the ambient temperature of the battery B). The controller 120 may perform a discharge event on the battery B in response to the completion of the polarization induction pretreatment. Alternatively, the polarization-induced pretreatment can be performed using separate test equipment instead of the evaluation device 10. FIG.

It can be seen from FIG. 2 that during a discharge event, a difference between the first reference voltage curve 210 and the first measured voltage curve 220 occurs, corresponding to the polarization difference between battery B and the reference battery. Specifically, the first measured voltage curve 220 exhibits a generally faster voltage decay behavior than the first reference voltage curve 210, and is referenced to the total discharge capacity _{QB_total} of battery B corresponding to the second critical voltage _VTH2 . It can be confirmed that the total discharge capacity Q _{ref_total} of the battery has decreased. This was due to the residual polarization of battery B being exhibited in the form of an overvoltage by the current of the discharge event.

As a result, the reference voltage history of the first reference voltage curve 210 and the measured voltage history of the first measured voltage curve 220 have the same voltage range, but the reference capacity history of the first reference voltage curve 210 and the first measured voltage curve 220 measured volume histories do not have the same volume range. Accordingly, the control unit 120 can measure the reference capacity history of the first reference voltage curve 210 and the first measured voltage curve 220 for ease of comparison between the first reference voltage curve 210 and the first measured voltage curve 220 . By normalizing each of the capacity histories, a first depth of discharge history and a second depth of discharge history can be determined that have the same range of 0-1 or 0-100%.

The reference capacity history and the first depth of discharge history of the first reference voltage curve 210 may have the following relationship.

Q _{ref_total} is the total discharge capacity of the first reference voltage curve 210, Q _ref [i] is the discharge capacity of the i-th determined reference battery during the discharge event, where i is a natural number greater than or equal to 1, DoD _ref [i] is a value obtained by normalizing Q _ref [i] using Q _{ref_total} . The first depth-of-discharge history may be a set (time series) of DoD _ref [i] during a discharge event.

The measured capacity history and the second depth of discharge history of the first measured voltage curve 220 may have the following relationship.

_{QB_total} is the total discharge capacity of the first measured voltage curve 220, _QB [j] is the i-th determined discharge capacity of battery B during the discharge event, where j is a natural number greater than or equal to 1, DoD _B [j] is a value obtained by normalizing _QB [j] using _{QB_total} . A second depth-of-discharge history may be a set (time series) of DoD _B [j] during a discharge event.

In FIG. 3, the X-axis (vertical axis) indicates voltage, and the Y-axis (horizontal axis) indicates the depth of discharge corresponding to the discharge capacity in FIG. Referring to FIG. 3, the control unit 120 converts the correspondence relationship between the reference capacity history and the reference voltage history into the correspondence relationship between the first depth-of-discharge history and the reference voltage history. Two reference voltage curves 310 may be determined.

Similarly, the control unit 120 converts the correspondence relationship between the measured capacity history and the measured voltage history of the first measured voltage curve 220 into the correspondence relationship between the second depth-of-discharge history and the measured voltage history. A second measured voltage curve 320 may be determined from curve 220 . As a result, the reference voltage history of the second reference voltage curve 220 and the measured voltage history of the second measured voltage curve 320 are scaled for a common range of depth of discharge of 0-100%.

In FIG. 4, the X-axis (vertical axis) indicates the differential voltage, and the Y-axis (horizontal axis) is the same as the Y-axis of FIG. Differential voltage dV/dQ indicates the ratio of voltage change dV to discharge capacity (or discharge depth) change dQ.

Referring to FIG. 4, the control unit 120 may determine a reference differential voltage curve 410 from the second reference voltage curve 310 by differentiating the reference voltage history of the second reference voltage curve 310 with respect to the first depth of discharge history.

Alternatively, the reference differential voltage curve 410 may be recorded in memory according to the results of pre-performed tests instead of being determined by the control unit 120 . That is, the reference differential voltage curve 410 may be predetermined as a differential voltage curve when a discharge event occurs in a state in which battery B is not subjected to polarization induction pretreatment (i.e., zero polarization).

The control unit 120 can determine the differentiated voltage curve 420 from the second measured voltage curve 320 by differentiating the measured voltage history of the second measured voltage curve 320 with respect to the second depth of discharge history. Differential voltage curve 420 shows (i) depth of discharge (or corresponding discharge capacity) and (ii) unit change in depth of discharge (or corresponding change in discharge capacity) over the entire range of 0 to 100%. ) and the rate of voltage change.

The control unit 120 compares the reference differential voltage curve 410 and the differential voltage curve 420 and determines the overvoltage characteristic information of the battery B from the differential voltage curve 420 . The control unit 120 may record the overvoltage characteristic information in the memory in association with the polarization induction pretreatment.

FIG. 5 is a graph illustrating a polarization comparison curve 500 showing the correspondence between the differential voltage difference ΔdV/dQ over the reference range ΔR _ref and the depth of discharge. In FIG. 5, the X-axis (vertical axis) indicates the differential voltage difference ΔdV/dQ, and the Y-axis (horizontal axis) is the same as the Y-axis in FIG.

The control unit 120 can determine the differential voltage difference ΔdV/dQ between the reference differential voltage curve 410 and the differential voltage curve 420 for the depth of discharge within the reference range ΔR _ref . The differential voltage difference ΔdV/dQ corresponding to each depth of discharge may be a value obtained by subtracting the differential voltage of the reference differential voltage curve 410 from the differential voltage of the differential voltage curve 420 . The reference range ΔR _ref ranges from a predetermined first depth of discharge DoD ₁ greater than 0% (eg 10%) to a predetermined second depth of discharge DoD ₂ less than 100% (eg 90%). The reason for using the reference range ΔR _ref is that the discharge reaction of the battery B is very unstable in the range of 0% to the first depth of discharge DoD ₁ and the range of the second depth of discharge DoD ₂ to 100%. .

The control unit 120 can determine the overvoltage concentration section ΔR _op , which is the range in which the differential voltage difference ΔdV/dQ of the polarization comparison curve 500 is equal to or greater than the critical difference ΔD in the entire range (ie, 0 to 100%) of the depth-of-discharge history. . The overvoltage characteristic information may include an overvoltage concentration interval ΔR _op . For example, in FIG. 5, the differential voltage of the differential voltage curve 420 is greater than the differential voltage of the reference differential voltage curve 410 by a critical difference ΔD or more over the overvoltage concentration section ΔR _op from the first depth of discharge DoD _A to the second depth of discharge DoD _B. maintained to a large extent. The critical difference ΔD can be a predetermined value. Alternatively, the control unit 120 can determine the critical difference ΔD based on the integrated value of the differential voltage difference ΔdV/dQ over the reference range ΔR _ref . For example, the controller 120 may determine the critical difference ΔD to be equal to the integrated value divided by the magnitude of the reference range ΔR _ref (ie, DoD ₂ −DoD ₁ ).

Controller 120 may further determine the area of overvoltage concentration region 430 . The overvoltage concentration region 430 is defined by the overvoltage concentration interval ΔR _op , the differential voltage curve 420 and the reference differential voltage curve 410 . The area of the overvoltage concentration region 430 is the difference between the voltage change of the second measured voltage curve 320 and the voltage change of the second reference voltage curve 310 over the overvoltage concentration interval ΔR _op . That is, the area of the overvoltage concentration region 430 indicates the amount of overvoltage accumulated in the battery B over the overvoltage concentration interval ΔR _op . The overvoltage characteristic information may further include the area of the overvoltage concentration region.

FIG. 6 is a flowchart illustrating a method for evaluating overvoltage characteristics of a battery according to a first embodiment of the invention. The method of FIG. 6 is performed after battery B has undergone polarization-induced pretreatment.

1 to 6, in step S610, the control unit 120 determines a measured capacity history and a measured voltage history that indicate time-series changes in the capacity and voltage, respectively, of the battery B during the discharging event of the battery B. do. The measured capacity history is based on the integrated current measured by the current sensor 112 at predetermined time intervals during the discharge event. The measured voltage history is based on the voltage across battery B measured by voltage sensor 111 at predetermined intervals during a discharge event.

At step S620, the controller 120 determines a first measured voltage curve 220 that indicates the correspondence relationship between the measured capacity history and the measured voltage history.

In step S630, the control unit 120 normalizes the measured capacity history to the total discharge capacity _{QB_total} of the measured capacity history, and creates a second measured voltage curve showing the correspondence relationship between the depth of discharge history corresponding to the measured capacity history and the measured voltage history. 320 is determined.

At step S<b>640 , the controller 120 differentiates the measured voltage history with respect to the discharge depth history to determine the differentiated voltage curve 420 from the second measured voltage curve 320 .

At step S650, the controller 120 determines a differential voltage difference between the differential voltage curve and the reference differential voltage curve for the depth of discharge within the reference range ΔR _ref .

In step S660, the control unit 120 determines an overvoltage concentration section ΔR _op in which the differential voltage difference is greater than or equal to the critical difference ΔD within the reference range ΔR _ref . The critical difference ΔD can be prerecorded in memory.

In step S<b>670 , the controller 120 determines the area of the overvoltage concentration region 430 defined by the overvoltage concentration section ΔR _op , the differential voltage curve 420 and the reference differential voltage curve 410 . Step S670 can be omitted from the method of FIG.

At step S680, the controller 120 outputs an evaluation message indicating the overvoltage characteristic information of the battery B. FIG. The overvoltage characteristic information includes at least one of the overvoltage concentration section ΔR _op and the area of the overvoltage concentration region 430 . The interface unit 130 may transmit the evaluation message to the user's terminal 2 or output visual and/or auditory information corresponding to the evaluation message.

FIG. 7 is a flowchart illustrating a method for evaluating overvoltage characteristics of a battery according to a second embodiment of the invention. The method of FIG. 7 is performed after the polarization-induced pretreatment for battery B is complete. In the description of the second embodiment, repetitive description of the contents common to the first embodiment may be omitted.

1 to 5 and 7, in step S710, the control unit 120 generates a measured capacity history and a measured voltage history that show time-series changes in the capacity and voltage of the battery B during the discharge event of the battery B. decide.

At step S720, the controller 120 determines a first measured voltage curve 220 that indicates the correspondence relationship between the measured capacity history and the measured voltage history.

In step S730, the control unit 120 normalizes the measured capacity history to the total discharge capacity _{QB_total} of the measured capacity history, and creates a second measured voltage curve showing the correspondence relationship between the depth of discharge history corresponding to the measured capacity history and the measured voltage history. 320 is determined.

At step S<b>740 , the controller 120 differentiates the measured voltage history with respect to the discharge depth history to determine the differentiated voltage curve 420 from the second measured voltage curve 320 .

At step S750, the controller 120 determines a differential voltage difference between the differential voltage curve 420 and the reference differential voltage curve 410 for the depth of discharge within the reference range ΔR _ref .

At step S752, the controller 120 determines whether the integral value of the differential voltage difference over the reference range ΔR _ref is greater than the reference integral value. If the value of step S752 is "yes", then proceed to step S756. If the value of step S752 is 'no', it may mean that an operation error occurred during steps S710 to S750. If the value of step S752 is "no", then proceed to step S754.

At step S754, the control unit 120 outputs a fault message. The interface unit 130 may transmit the fault message to the user's terminal 2 or output visual and/or auditory information corresponding to the fault message. Steps S752 and S754 may be omitted from the method of FIG. 7, and step S756 may be performed after step S750.

At step S756, the controller 120 determines the critical difference ΔD based on the integral value of the differential voltage difference over the reference range ΔR _ref .

In step S760, the control unit 120 determines an overvoltage concentration section ΔR _op in which the differential voltage difference is greater than or equal to the critical difference ΔD within the reference range ΔR _ref .

In step S<b>770 , the controller 120 determines the area of the overvoltage concentration region 430 defined by the overvoltage concentration section ΔR _op , the differential voltage curve 420 and the reference differential voltage curve 410 . Step S770 can be omitted from the method of FIG.

In step S780, the controller 120 outputs an evaluation message indicating the overvoltage characteristic information of the battery B. FIG. The overvoltage characteristic information includes at least one of the critical difference ΔD, the overvoltage concentration section ΔR _op and the area of the overvoltage concentration region 430 .

The embodiments of the present invention described above are not necessarily embodied through devices and methods, but are embodied through programs that implement functions corresponding to configurations of the embodiments of the present invention or recording media on which the programs are recorded. Such implementation should be easily implemented by those skilled in the technical field to which the present invention belongs, based on the description of the above-described embodiments.

Although the present invention has been described above with reference to the limited embodiments and drawings, the present invention is not limited thereto, and a person having ordinary knowledge in the technical field to which the present invention belongs can understand the technical concept of the present invention and the scope of the claims. It goes without saying that various modifications and variations are possible within the equivalent range of .

In addition, the above-described present invention can be variously replaced, modified, and changed within the scope of the technical idea of the present invention by a person having ordinary knowledge in the technical field to which the present invention belongs. And it is not limited by the attached drawings, and all or part of each embodiment can be selectively combined so as to make various modifications.

Claims (10)

An overvoltage characterization device for a battery, comprising:
a sensing unit configured to measure current and voltage of the battery;
Using the sensing information obtained from the sensing unit during a discharge event that is performed subsequent to polarization-inducing pretreatment for the battery, a measured capacity history and a measured voltage history that indicate time-series changes in capacity and voltage of the battery are generated. a control unit that determines
The control unit
Determining a first measured voltage curve indicating a correspondence relationship between the measured capacity history and the measured voltage history,
Determining a second measured voltage curve showing a correspondence relationship between the depth of discharge history obtained by normalizing the measured capacity history to the total discharge capacity of the measured capacity history and the measured voltage history,
differentiating the measured voltage history with respect to the depth of discharge history;
determining a differential voltage curve from the second measured voltage curve;
Comparing the differential voltage curve with a reference differential voltage curve,
An overvoltage characteristic evaluation device for determining overvoltage characteristic information related to the polarization induction pretreatment. the discharge event includes a constant current discharge from a first time point to a second time point;
the first point in time is a point in time when the voltage of the battery is the same as a first critical voltage;
2. The apparatus for evaluating overvoltage characteristics of claim 1, wherein the second point in time is the same point in time as a second critical voltage when the voltage of the battery is lower than the first critical voltage. The control unit
determining an overvoltage concentration section, which is a range in which a differential voltage difference between the differential voltage curve and the reference differential voltage curve is equal to or greater than a critical difference in the entire range of the depth-of-discharge history;
3. The overvoltage characteristic evaluation device according to claim 1, wherein said overvoltage characteristic information includes said overvoltage concentrated section. The control unit
determining an area of an overvoltage concentration region defined by the overvoltage concentration section, the differential voltage curve, and the reference differential voltage curve;
4. The overvoltage characteristic evaluation apparatus according to claim 3, wherein said overvoltage characteristic information further includes the area of said overvoltage concentrated region. The area is
5. The overvoltage characteristic evaluation apparatus of claim 4, which indicates the magnitude of the overvoltage accumulated in the battery over the overvoltage concentration interval. The control unit
The critical difference is obtained by dividing the integrated value of the differential voltage difference over a reference range from a predetermined first depth of discharge to a predetermined second depth of discharge within the entire range of the depth of discharge history by the size of the reference range. 6. The overvoltage characterization device according to any one of claims 3 to 5, wherein the overvoltage characterization device determines. The control unit
7. The overvoltage characteristic evaluation apparatus according to claim 6, wherein said overvoltage concentration section is determined within said reference range. An overvoltage characterization method for a battery, comprising:
a measured capacity history indicating changes in capacity and voltage of the battery over time using current and voltage sensing information of the battery obtained during a discharge event subsequent to a polarization-induced pretreatment for the battery; and determining a measured voltage history;
Determining a first measured voltage curve indicating a correspondence relationship between the measured capacitance history and the measured voltage history;
Determining a second measured voltage curve indicating a correspondence relationship between the depth of discharge history obtained by normalizing the measured capacity history to the total discharge capacity of the measured capacity history and the measured voltage history;
differentiating the measured voltage history with respect to the depth of discharge history to determine a differentiated voltage curve from the second measured voltage curve;
and comparing the differential voltage curve with a reference differential voltage curve to determine overvoltage characteristic information related to the polarization-induced pretreatment. The step of determining the overvoltage characteristic information related to the polarization induction pretreatment includes overvoltage concentration in a range in which a differential voltage difference between the differential voltage curve and the reference differential voltage curve is equal to or greater than a critical difference in the entire range of the depth-of-discharge history. 9. The overvoltage characterization method of claim 8, comprising determining an interval. The step of determining overvoltage characteristic information related to the polarization-induced pretreatment includes:
10. The method of claim 9, further comprising determining an area of an overvoltage concentration region defined by the overvoltage concentration section, the differential voltage curve and the reference differential voltage curve.

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